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This is the Burglar Alarms FAQ page.
Here you will find various Frequently asked Questions (FAQ) about alarm terminology, problems, and links to the hints section.
Q: What is a SAB?
A: This is a SELF ACTIVATING BELL module. It is an electronic module inside a bell-box that will activate the sounder if the wires feeding the voltage to the “hold-off circuit” are cut. It is normally powered by a SAB BATTERY that is kept constantly charged by the 12 volt feed, sometimes supplmented by SOLAR CELLS.
Q: How long will the backup battery keep the panel active if power is lost?
A: This is dependent on the the AMP-HOUR figure on the battery in the alarm panel, and the current being drawn while the system is set. The panel itself will be drawing about 100 to 200 Mili-amps, and the PIR’s will be using about 10 to 25mA each. Door magnets do not use any power, but add in any glass-break sensors. So, if your alarm panel load is 100mA plus the 15mA bell hold-off circuit, and 6 PIRS at 10mA (that is worst case with LED on, most run at 5mA) that totals 175mA), So, if you have a 4aH battery installed, that should provide 4,000 mA for one hour, or 175mA for a theoretical 22.9 HOURS. However, the voltage would drop to below the threshold to operate the electronics properly after about 11 hours. Always try to fit the largest capacity battery that will fit into the panel, to give the longest possible backup time.
Q: Can I fit more than one PIR on to a zone?
A: Yes, this is easy to accomplish , please see the HINTS section HERE. However, unless you have latching PIR’s you might not knowwhich one was triggered.
Q: Can I fit different sensor types onto one zone?
A: Yes, just remember to ensure that all contacts and tamper loops are serial wired, and all required power is continued though to the last sensor in the zone. If a particular sensor has an option for N.C or N.O. then choose the N.O. pair, as this means “Normally Open”. That is, the contact state or position at rest, where the magnet is NOT close enough to keep the contacts closed (i.e. window or door in the shut position). This should match any PIR contacts state when not activated by an alarm condition. Also see the hint HERE and wiring picture HERE.
Q: How long will the backup battery last, and how do I test it?
A: This is dependent on the the make, quality of manufacture, and the conditions under which it is housed and charged. However, do not expect the standard sealed lead-acid batteries to last more than 10 years. It is a good adea to test it periodically, at least once per year if possible. Some commercial panels have a battery test button, but most domestic ones do not. If you installed it yourself, and know the engineers code, then you MAY be able to put the panel in engineeer mode, carefully disconnect one battery terminal, measure the voltage with a meter for around 12 VOLTS. Wait for 20 minutes, and test again. If it drops below 11 VOLTS, then your battery is probably nearing the end of its life. Look for any area bulging or cracking on the case as well. NOTE: It would be wise to have your program codes handy, in case you need to key them in again (should the mains fail while you have the battery disconnected). Reconnect your battery, and test all alarm functions.
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